Bipolar end effector apparatus for a surgical instrument

ABSTRACT

An end effector apparatus for a surgical instrument is disclosed including a housing having a first jaw mounted on a revolute joint and providing a first electrical conduction path between the housing and the first jaw. A second jaw is mounted on a revolute joint within the housing and is insulated from the housing, the jaws each having a manipulating portion and a lever arm. A yoke is received within the housing and mechanically coupled to the lever arms and to a control link and is moveable in response to movements of the control link to cause opening and closing of the jaws, the yoke being electrically insulated from the housing and the first jaw. A second electrical conduction path is provided between the control link and the second jaw. The electrical conduction paths facilitate conduction of an electrocauterization current through tissue grasped between the jaws.

BACKGROUND 1. Field

This disclosure relates generally to an apparatus used for surgicalprocedures and more particularly to an end effector for a robotic and/orlaparoscopic surgical instrument.

2. Description of Related Art

Remotely actuated surgical instruments may be used in laparoscopicand/or robotic surgery applications where there is an area of limitedaccess for an operator. The surgical instrument generally includes anend effector disposed at a distal end of a shaft and an actuator portionfor manipulating the end effector at a proximate end of a shaft. The endeffector and a portion of the surgical instrument inserted through anincision into a body cavity of a patient while the actuator portiongenerally remains outside the body cavity.

End effectors having opposing pivoting jaws are used for grasping andmanipulating tissue during surgery and it may be desirable to couple ahigh frequency alternating current through the jaws for performingelectrocauterization of tissue. In some cases, the electrocauterizationcurrent may be supplied by a current generator through a unipolar endeffector with the return current path being provided through a groundconnection in contact with the patient's body. There however remains aneed for bipolar end effectors having two jaws, in which anelectrocauterization current is supplied through the first jaw, flowsthrough tissue clamped between the two jaws, and is returned through thesecond jaw.

SUMMARY OF THE INVENTION

In accordance with one disclosed aspect there is provided an endeffector apparatus for a surgical instrument. The apparatus includes ahousing, a first jaw mounted on a revolute joint within the housing soas to provide a first electrical conduction path between the housing andthe first jaw. The first jaw has a manipulating portion extendingforwardly and a lever arm projecting rearwardly from the revolute joint.The apparatus also includes a second jaw mounted on a revolute jointwithin the housing and electrically insulated from the housing, thesecond jaw having a manipulating portion extending forwardly from therevolute joint and a lever arm projecting rearwardly from the revolutejoint. The apparatus further includes a yoke received within the housingand mechanically coupled to the respective lever arms of the first andsecond jaws and to a control link, the yoke being moveable with respectto the housing in response to movements of the control link whenactuated by the surgical instrument, the movement of the yoke beingoperable to cause opening and closing movements of the first and secondjaws about the respective revolute joints. The yoke is electricallyinsulated from the housing and the first jaw. The apparatus alsoincludes a second electrical conduction path between the control linkand the second jaw, the first and second electrical conduction pathsfacilitating conduction of a electrocauterization current through tissuegrasped between the first and second jaws.

The first jaw may be mounted on a first revolute joint within thehousing and the second jaw is mounted on a second revolute joint withinthe housing.

The first jaw and the second jaw may be mounted on a common revolutejoint within the housing.

The housing may include an outer clevis and the common revolute jointmay include a pivot pin extending between a pair of arms associated withthe outer clevis.

The yoke may include an inner clevis having arms configured to receivethe respective lever arms of the first and second jaws.

The second jaw may be mounted on an insulating spacer received on thepivot pin.

The apparatus may include a torque tube coupled to the housing, thetorque tube being operable to cause rotation of the housing whenactuated by the surgical instrument and the torque tube may be inelectrical connection with the housing for carrying theelectrocauterization current.

The control link may be received within a bore of the torque tube andmay further include an electrically insulating sheath between thecontrol link and the torque tube and the control link and torque tubemay be operable to connect to respective poles of a bipolarelectrocautery current generator.

The torque tube, insulating sheath, and control link may be configuredto flex within an articulated tool positioner to permit dexterousmovement of the end effector apparatus.

The housing may include an electrically conductive material and mayfurther include an electrically conductive washer disposed on therevolute joint between the first jaw and the housing for providing thefirst electrical conduction path.

The housing may include an outer clevis and the yoke may include aninner clevis having arms configured to receive the respective lever armsof the first and second jaws.

The yoke may include an electrically insulating material and the controllink extends through the yoke and may have a portion in sliding contactwith the second jaw for completing the second electrical conductionpath.

The portion of the control link in sliding contact with the second jawmay include a conductive tab having a surface that contacts the secondjaw.

The lever arms associated with the first and second jaws each mayinclude a slot and the yoke may include a pin slidingly received withinthe respective slots for providing the mechanical coupling between theyoke and the lever arms.

The slot may include an arcuate slot.

The pin may include an insulated portion received within the slot in thelever arm of the first jaw, and a conductive pin portion received withinthe slot in the lever arm of the second jaw for completing the secondelectrical conduction path between the control link and the second jaw.

The housing may include an insulating material and the first electricalconduction path between the housing and the first jaw may be provided bya conductor running through the housing and having a portion in slidingcontact with the first jaw.

The apparatus may include a linkage extending between the lever armassociated with at least one of the first and second jaws and the yokefor providing the mechanical coupling between the yoke and the leverarm.

In accordance with another disclosed aspect there is provided a methodfor actuating an end effector for a surgical instrument, the endeffector includes a housing, a first jaw mounted on a revolute joint soas to provide a first electrical conduction path between the housing andthe first jaw, the first jaw having a manipulating portion extendingforwardly from the revolute joint and a lever arm projecting rearwardlyfrom the revolute joint, a second jaw mounted on a revolute joint andelectrically insulated from the housing, a second electrical conductionpath between a control link and the second jaw, the second jaw having amanipulating portion extending forwardly from the revolute joint and alever arm projecting rearwardly from the revolute joint, a yoke receivedwithin the housing and being mechanically coupled to respective leverarms of the first and second jaws and to a control link, the yoke beingelectrically insulated from the housing and the first jaw. The methodinvolves causing movement of the yoke with respect to the housing inresponse to movements of the control link to cause opening and closingmovements of the first and second jaws about the revolute joints, andcoupling an electrocauterization current through the first and secondelectrical conduction paths and through tissue grasped between the firstand second jaws.

Other aspects and features will become apparent to those ordinarilyskilled in the art upon review of the following description of specificdisclosed embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate disclosed embodiments,

FIG. 1 is a perspective view of an end effector apparatus according to afirst disclosed embodiment;

FIG. 2 is a perspective view of the end effector apparatus shown in FIG.1 in an open condition with a housing portion partially cut away;

FIG. 3 is a perspective view of the end effector apparatus shown in FIG.2 in a closed condition;

FIG. 4 is an exploded perspective view of a portion of the end effectorshown in FIG. 1;

FIG. 5 is an exploded perspective view of another portion of the endeffector shown in FIG. 1;

FIG. 6 is perspective view of the portion of the end effector shown inFIG. 5 in an assembled condition;

FIG. 7 is a perspective view of a portion of a housing and inner clevisof an end effector apparatus according to an alternative embodiment;

FIG. 8 is a perspective view of another disclosed embodiment of an endeffector apparatus;

FIG. 9 is a perspective view of the end effector shown in FIG. 8 with aportion of a housing cut away;

FIG. 10 is an exploded perspective view of the end effector shown inFIG. 8;

FIG. 11 is a perspective view of a further disclosed embodiment of anend effector apparatus;

FIG. 12 is a perspective view of the end effector shown in FIG. 11 witha portion of a housing cut away; and

FIG. 13 is an exploded perspective view of the end effector shown inFIG. 11.

DETAILED DESCRIPTION

Referring to FIG. 1, an end effector apparatus according to a firstdisclosed embodiment is shown generally at 100. The end effector 100 isconnected via a shaft 220 to a surgical instrument 230. The surgicalinstrument 230 includes an input 232 for receiving a current from abipolar electrocautery generator 240 via a cable 242.

In one embodiment, the surgical instrument 230 may be anelectro-mechanical interface to a robotic surgery system for controllingand actuating the end effector. For example, the surgical instrument maybe configured as an articulated tool positioner as described in detailin commonly owned patent applications PCT/CA2013/001076 entitled“ARTICULATED TOOL POSITIONER AND SYSTEM EMPLOYING SAME” andPCT/CA2015/000098 entitled “ACTUATOR AND DRIVE FOR MANIPULATING A TOOL”filed on Feb. 18, 2015. In other embodiments the surgical instrument maybe a hand operated laparoscopic tool actuator that is manipulateddirectly by a surgeon.

The end effector 100 includes a housing 102 and a revolute joint 104received between first and second arms 180 and 182 of the housing thatdefine an outer clevis. The end effector 100 also includes a first jaw106 and a second jaw 108 mounted on the revolute joint 104. In thisembodiment the revolute joint 104 is a common revolute joint and thefirst and second jaws 106 and 108 are mounted on the same revolutejoint. In other embodiments, the first and second jaws 106 and 108 maybe mounted on separate spaced apart revolute joints within the housing102. The first and second jaws 106 and 108 each have respectivemanipulating portions 110 and 112 extending forwardly from the revolutejoint 104 and respective lever arms 114 and 116 projecting rearwardlyfrom the revolute joint. In this embodiment the first and second jaws106 and 108 are fabricated from an electrically conductive material.

The end effector 100 also includes an inner clevis 118 received withinthe housing 102. The end effector 100 is shown in FIG. 2 in enlargeddetail with the housing 102 partially removed to better show the innerclevis 118. Still referring to FIG. 1, the inner clevis 118 isreciprocally moveable within the housing 102 in a direction indicated bythe arrow 222. The inner clevis 118 is sized to slide within the housing102. In this embodiment, the housing includes a slot 120 and the innerclevis 118 includes a sliding pin 122, which is received in the slot andguides the reciprocating motion of the inner clevis within the housing.An additional slot may be disposed on the opposite side of the housing102 (not visible in FIG. 1 and FIG. 2) for receiving a second slidingpin associated with the inner clevis 118. The sliding pins preventrotation of the inner clevis 118 within the housing 102, which may causebinding between surfaces of the inner clevis and surfaces of thehousing.

The jaws 106 and 108 are shown in an open configuration in FIG. 2, whichcorresponds to the inner clevis 118 having been moved forwardly towardthe revolute joint 104 of the end effector 100. Referring to FIG. 3 thejaws 106 and 108 are shown in a closed configuration, which correspondsto the inner clevis 118 having been moved rearwardly away from therevolute joint 104 of the end effector 100. In this embodiment the innerclevis 118 acts as a yoke for coupling a force applied to the innerclevis to the respective lever arms 114 and 116.

In this embodiment the housing 102 is fabricated from an electricallyconductive material such as stainless steel, the inner clevis 118 isfabricated from an electrically insulating material such as a plastic(for example Polyetherimide manufactured under the name Ultem by SaudiArabia Basic Industries Corporation), and the first and second jaws 106and 108 are fabricated from stainless steel.

The end effector 100 is shown in exploded view in FIG. 4. Referring toFIG. 4, the revolute joint 104 is aligned along an axis 128 and includesa pivot pin 130 and an insulating spacer 132 received on the pivot pin.The pivot pin 130 is supported between the first and second arms 180 and182 of the housing 102 (shown in FIG. 1). The insulating spacer 132electrically insulates the first jaw 106 from the second jaw 108 whenreceived on the pivot pin 130. The first jaw 106 includes an opening 134and is received on the pivot pin 130 to permit the jaw to pivot freelyabout the pin. The revolute joint 104 also includes an insulating spacer138, which has a protruding annular portion 140 and an opening 139 sizedto be received on the pivot pin 130. The second jaw 108 further includesan opening 136 that is sized to receive the protruding portion 140 ofthe insulating spacer 138, which is in turn received together with thesecond jaw on the pivot pin 130. The insulating spacer 138 electricallyinsulates the second jaw 108 from the pivot pin 130.

The first jaw 106 has a protruding annular portion 142 (also shown inFIG. 2), which in this embodiment is formed as a unitary part of theelectrically conductive second jaw. The revolute joint 104 furtherincludes an electrically conductive washer 144, which is received on thepivot pin 130 and completes an electrical connection between theprotruding annular portion 142 of the first jaw 106 and the housing 102.In the embodiment shown the washer 144 is a spring washer, such as aBellville or wave washer that compresses when received between theprotruding annular portion 142 and the housing 102. The spring washer144 is compressed when the revolute joint 104 is assembled within thehousing and is able to extend laterally to facilitate an electricalconnection between the revolute joint 104 received between the first arm180 of the housing 102 and the first jaw 106.

The inner clevis 118 includes a first slot 150 defined between first andsecond tines 152 and 154 for receiving the lever arm 114 of the firstjaw 106. The inner clevis 118 also includes a second slot 156 definedbetween the second tine 154 and a third tine 158 for receiving the leverarm 116 of the second jaw 108. The inner clevis 118 further includes anopening 160 extending through the first tine 152 for receiving a pin 162and an opening 164 extending through the third tine 158 for receiving apin 166. The second tine 154 may have corresponding openings (notvisible in FIG. 4) for receiving the pins 162 and 166 such that each ofthe pins is retained between a pair of tines.

The lever arm 114 of the first jaw 106 further includes an arcuate slot170 and the lever arm 116 of the second jaw 108 includes an arcuate slot172. When the end effector 100 is assembled the lever arm 114 of thefirst jaw 106 is received in the slot 150 and the pin 162 is pressedthrough the opening 160 and through the arcuate slot 170 to mechanicallycouple the inner clevis 118 to the first jaw. Similarly, the lever arm116 of the second jaw 108 is received in the slot 156 and the pin 166 ispressed through the opening 164 and through the arcuate slot 172 tomechanically couple the inner clevis 118 to the second jaw. Referringback to FIG. 2, when the inner clevis 118 is actuated to move toward therevolute joint 104 the pins 162 and 166 slide forwardly along therespective arcuate slots 170 and 172 causing the respective jaws 106 and108 to pivot about the revolute joint 104 to open. Similarly, referringto FIG. 3, when the inner clevis 118 is actuated to move away from therevolute joint 104 the pins 162 and 166 slide rearwardly along therespective arcuate slots 170 and 172 causing the respective jaws 106 and108 to pivot about the revolute joint 104 to close.

Referring back to FIG. 1 the shaft 220 includes a control link 190 and atorque tube 192, each of which are fabricated from electricallyconducting material. The shaft 220 also includes an electricallyinsulating sheath 194 between the control link 190 and the torque tube192 and an electrically insulating sheath 196 covering the torque tube.The electrically insulating sheath 194 is sized to permit freereciprocating movement of the control link 190 within the sheath. In oneembodiment the torque tube 192, the insulating sheaths 194 and 196, andthe control link 190 are fabricated from flexible materials that permitthe shaft 220 to flex within an articulated tool positioner (not shown)that permits dexterous movement of the end effector apparatus 100.

Referring to FIG. 2, the torque tube 192 is received within a collar 202of the housing 102. The torque tube 192 is also mechanically coupled tothe collar 202 to permit rotation of the housing 102 and thus the endeffector 100 in the direction indicated by the arrow 198. The collar 202also provides an electrical connection between the torque tube 192 andthe electrically conductive housing 102. In one embodiment the torquetube 192 may be soldered, welded, or crimped to the collar 202 of thehousing 102. The torque tube 192 thus provides a first electricalconnection through the housing 102, through the electrically conductivewasher 144 (shown in FIG. 4) and the annular portion 142 to the firstjaw 106. At the same time, the insulating spacers 132 and 138 functionto insulate the second jaw 108 from the first jaw 106.

The inner clevis 118, second jaw 108, and the control link 190 of theend effector 100 are shown in exploded view in FIG. 5 and as assembledin FIG. 6. A face of the inner clevis 118 that is oriented toward therevolute joint 104 is shown while the first jaw 106 has been removedfrom the first slot 150 to reveal connections to the second jaw 108. Asdisclosed above, the inner clevis 118 is fabricated from an insulatingmaterial and there is thus no inherent electrical connection between thefirst jaw and the inner clevis. Referring to FIG. 5, electricalconnection between the control link 190 and the lever arm 116 of thesecond jaw 108 is provided through a conductive tab 300. The conductivetab 300 includes a recess 302 for receiving the control link 190, whichin one embodiment may be soldered to the conductive tab 300. The controllink 190 also includes a ferrule 304, which is securely connected to thecontrol link. The ferrule 304 provides an attachment point formechanically connecting the control link 190 to the inner clevis 118 tofacilitate movement of the inner clevis within the housing 102 inresponse to reciprocating movement of the control link. The control link190, ferrule 304 and the conductive tab 300 are received in an opening306 on the second tine 154 of the inner clevis 118. The ferrule 304 ismechanically secured to the inner clevis by means of an adhesive, athreaded connection, crimping or other fastening method. The innerclevis 118 is thus actuated to move with respect to the housing 102 inresponse to movements of the control link 190 when actuated by thesurgical instrument 230 (shown in FIG. 1). The movement of the innerclevis 118 is operable to cause opening and closing movements of thefirst and second jaws 106 and 108 about the revolute joint 104.

The lever arm 116 of the second jaw 108 is received within the secondslot 156 and a spring washer 308 is inserted between the third tine 158and the second jaw to urge a surface 310 of the lever arm 116 intosliding electrical connection with the conductive tab 300. The secondjaw 108 and spring washer 308 are retained within the second slot 156 bythe pin 166, which is pressed through the opening 164 and through thearcuate slot 170 in the lever arm 116. The control link 190 thusprovides a second electrical conduction path through the conductive tab300 to the second jaw 108. The insulating spacers 132 and 138 (shown inFIG. 1) insulate the second jaw 108 from the first jaw 106 and thehousing 102. The inner clevis 118 is thus electrically insulated fromthe housing 102 and the first jaw 106. At the same time the control link190 is also mechanically coupled to the inner clevis 118 for actuatingthe inner clevis to move within the housing 102 to cause the jaws 106and 108 to open and close.

The first and second electrical conduction paths between the controllink 190 and first jaw 106 and the torque tube 192 and second jaw 108are thus independent, and facilitate conduction of theelectrocauterization current through tissue grasped between the firstand second jaws 106 and 108. The two independent electrical conductionpaths eliminate the need for additional cables that would usually berequired to carry an electrocauterization current through the shaft tothe jaws. Additional cables occupy space within the shaft and mayrequire increased shaft diameter to accommodate the cables. Thedisclosed embodiment, by combining the mechanical and electricalactuation functions within a single link or tube, facilitates bipolaroperation of the end effector 100 without an increase in size and/orcomplexity of the shaft 220.

An alternative embodiment of the end effector is shown in FIG. 7 at 400.Referring to FIG. 7, an inner clevis 402 of the end effector 400 has acircular shape and is received within a housing 404 that has a circularbore for receiving the inner clevis. The inner clevis 402 is otherwiseconfigured generally as described above in connection with the innerclevis 118, with the exception of the sliding pin 122 and the slot 120.In the end effector 400 the sliding pins may be omitted since thecircular inner clevis 402 permits some rotation within the housing 404without causing binding between the components.

An alternative embodiment of an end effector apparatus for a surgicalinstrument is shown in FIGS. 8 to 10 at 500. Referring to FIG. 8, theend effector 500 includes a housing 502 and a first jaw 504 mounted on arevolute joint 506 within the housing. The first jaw 504 has amanipulating portion 508 extending forwardly and a lever arm 510projecting rearwardly from the revolute joint (better shown in FIG. 9,where a portion of the housing 502 is cut away to reveal the lever arm510).

The end effector 500 also includes a second jaw 512 mounted on therevolute joint 506, which in this embodiment is a common revolute joint.An exploded view of the end effector 500 is shown in FIG. 10. Referringto FIG. 10, the second jaw 512 includes a manipulating portion 514extending forwardly from the revolute joint 506 and a lever arm 516projecting rearwardly from the revolute joint. The lever arm 516 andmanipulating portion 514 are better shown in an exploded view in FIG.10.

Referring to FIGS. 9 and 10, the end effector 500 also includes a yoke518 received within the housing 502 and mechanically coupled to therespective lever arms 510 and 516 of the first and second jaws 504 and512 and to a control link 520. The yoke 518 is moveable with respect tothe housing 502 in response to movements of the control link 520 whenactuated by the surgical instrument. Movement of the yoke 518 causesopening and closing movements of the first and second jaws 504 and 512about the revolute joint 506. The first and second jaws 504 and 512 arefabricated from an electrically conductive material such as stainlesssteel.

The revolute joint 506 includes an electrically conductive washer 522mounted between the first jaw 504 and the housing 502, which provides afirst electrical conduction path between the housing and the first jaw.In one embodiment the electrically conductive washer 522 may be a springwasher. The second jaw 512 is electrically insulated from the housing byan insulating spacer 524 that inserts in the housing between the secondjaw and an arm 526 of the housing. In the embodiment shown the revolutejoint 506 includes a pivot pin 528 and the insulating spacer 524includes an insulating bushing 530 that extends through the second jaw512 over the pivot pin. The pivot pin 528 and insulating spacer 524 thusprovide a revolute mounting for the second jaw 512 within the housing502 that insulates the second jaw from the housing. In this embodimentan additional insulating washer 529 is received on the pivot pin 528 andprovides insulation between the first jaw 504 and the second jaw 512.

Referring to FIG. 10, the yoke 518 includes an electrically conductivepin 532 that is slidingly received in a slot 534 in the lever arm 516and provides the mechanical coupling between the yoke and the lever arm.In this embodiment the pin 532 is electrically connected via the yoke518 to the control link 520 providing a second electrical conductionpath between the control link and the second jaw 512. The yoke 518 alsoincludes a pin 536 for engaging a slot 538 in the lever arm 510 thatprovides the mechanical coupling between the yoke and the lever arm.However in this case the pin 536 is insulated from the yoke 518 so thatthe first jaw 504 remains isolated from the yoke and thus the secondelectrical conduction path. The yoke 518 and may be fabricated using ametal injection molding process and the electrically conductive pin 532may be fabricated as part of the yoke. The pin 536 may be provided as aninsulating insert that attaches to the yoke. In one embodiment the yokemay be a stainless steel material that is coupled directly to thecontrol link (for example, by crimping), providing the electricalcontact to the yolk. The yoke 518 is electrically insulated from thehousing 502, and if necessary, an insulating overmold or otherinsulating components may be used to provide the electrical isolationbetween the yoke 518, housing 502, and the first jaw 512.

The first and second electrical conduction paths facilitate conductionof a electrocauterization current through tissue grasped between thefirst and second jaws 504 and 512. For example, as described above thetorque tube 192 may couple to the housing to provide a connection fromthe bipolar electrocautery generator 240, via the housing 502, and tothe first jaw 504. The control link 520 may provide a connection betweenthe bipolar electrocautery generator 240 and the second jaw 512.

A further embodiment of an end effector apparatus for a surgicalinstrument is shown in FIGS. 11 to 13 at 600. Referring to FIG. 11, theend effector 600 includes a housing 602 and a first jaw 604 mounted on afirst revolute joint 606 within the housing. The end effector 600 isshown in FIG. 12 with a portion of the housing 602 cut away and inexploded view in FIG. 13. The first jaw 604 has a manipulating portion608 extending forwardly and a lever arm 610 (shown in FIGS. 12 and 13)projecting rearwardly from the revolute joint 606.

The end effector 600 also includes a second jaw 612 mounted on a secondrevolute joint 614. The second jaw 612 includes a manipulating portion616 extending forwardly from the revolute joint 606 and a lever arm 618projecting rearwardly from the revolute joint. In this embodiment thefirst revolute joint 606 and the second revolute joint 614 arevertically separated within the housing 602, which may improve grippingforce when the first and second jaws 604 and 612 are actuated to close.

Referring to FIGS. 11 and 12, the end effector 600 also includes a yoke620 received within the housing 602 and mechanically coupled to therespective lever arms 610 and 618 of the first and second jaws 604 and612 and to a control link 622. The yoke 620 is moveable with respect tothe housing 602 in response to movements of the control link 622 whenactuated by the surgical instrument. Movement of the yoke 620 causesopening and closing movements of the first and second jaws 604 and 612about the respective revolute joints 606 and 614. The first and secondjaws 604 and 612 are fabricated from an electrically conductive materialsuch as stainless steel.

The embodiment shown in FIGS. 11-13 differs from that shown in FIGS.8-10 in that the housing 602 is fabricated from a non-conductivematerial such as a Polyetherimide and thus there is no electricalconnection directly between the housing and the either of the jaws 604and 612. Referring to FIG. 13, the first revolute joint 606 includes apin 624 and an electrically conductive washer 626 (such as a springwasher) mounted on the pin. The washer 626 also includes a conductorportion 628 that runs through the housing and emerges at a slot 629 inthe rear of the housing 602. When assembled the washer 626 contacts thefirst jaw 604 and thus provides a first electrical conduction paththrough the conductor portion 628, via the washer 626, and to the firstjaw 604. The first jaw 604 thus remains insulated from the housing 602,since the housing is non-conductive.

The second revolute joint 614 includes a pin 625 for mounting the secondjaw 612, which is also electrically insulated from the housing. The yoke620 is shown in further detail in an insert in FIG. 13. The yoke 620includes an electrically conductive center portion 640 and also includesan insulated pin 630 that slidingly engages a slot 632 in the lever arm610. The insulated pin 630 is provided as an insulating insert. The yoke620 also includes a conductive pin 642 and conductive spring washer,which when engaged with a slot 646 in the lever arm 618 provides asecond electrical conduction path through the control link 622, via theyoke 620, to the second jaw 612. The yoke 620 need not be insulated fromthe housing 602 in this embodiment since the housing is non-conductive.

The first and second electrical conduction paths facilitate conductionof a electrocauterization current through tissue grasped between thefirst and second jaws 604 and 612.

While specific embodiments have been described and illustrated, suchembodiments should be considered illustrative only and not as limitingthe invention as construed in accordance with the accompanying claims.

What is claimed is:
 1. An end effector apparatus for a surgicalinstrument, the apparatus comprising: a housing including an outerclevis; a first jaw mounted on a revolute joint within the housing so asto provide a first electrical conduction path between the housing andthe first jaw, the first jaw having a manipulating portion extendingforwardly and a lever arm projecting rearwardly from the revolute jointmounting the first jaw; a second jaw mounted on a revolute joint withinthe housing and electrically insulated from the housing, the second jawhaving a manipulating portion extending forwardly from and a lever armprojecting rearwardly from the revolute joint mounting the second jaw; ayoke received within the housing and mechanically coupled to therespective lever arms of the first and second jaws and to a controllink, the yoke being moveable with respect to the housing in response tomovements of the control link when actuated by the surgical instrument,the movement of the yoke being operable to cause opening and closingmovements of the first and second jaws about the respective revolutejoints, the yoke being electrically insulated from the housing and thefirst jaw, the yoke including: an inner clevis having arms configured toreceive the respective lever arms of the first and second jaws; and anelectrically insulating material; and a second electrical conductionpath between the control link and the second jaw, the first and secondelectrical conduction paths facilitating conduction of anelectrocauterization current through tissue grasped between the firstand second jaws, wherein the control link extends through the yoke andhas a portion in sliding contact with the second jaw for completing thesecond electrical conduction path.
 2. The apparatus of claim 1 whereinthe revolute joint includes a first revolute joint and a second revolutejoint, and wherein the first jaw is mounted on the first revolute jointwithin the housing and the second jaw is mounted on the second revolutejoint within the housing.
 3. The apparatus of claim 1 wherein the firstjaw and the second jaw are mounted on a common revolute joint within thehousing.
 4. The apparatus of claim 3 wherein the common revolute jointincludes a pivot pin extending between a pair of arms associated withthe outer clevis.
 5. The apparatus of claim 4 wherein the yoke comprisesan inner clevis having arms configured to receive the respective leverarms of the first and second jaws.
 6. The apparatus of claim 4 whereinthe second jaw is mounted on an insulating spacer received on the pivotpin.
 7. The apparatus of claim 1 further comprising a torque tubecoupled to the housing, the torque tube being operable to cause rotationof the housing when actuated by the surgical instrument and wherein thetorque tube is in electrical connection with the housing for carryingthe electrocauterization current.
 8. The apparatus of claim 7 whereinthe control link is received within a bore of the torque tube andfurther comprising an electrically insulating sheath between the controllink and the torque tube and wherein the control link and torque tubeare operable to connect to respective poles of a bipolar electrocauterycurrent generator.
 9. The apparatus of claim 8 wherein the torque tube,insulating sheath, and control link are configured to flex within anarticulated tool positioner to permit dexterous movement of the endeffector apparatus.
 10. The apparatus of claim 1 wherein the housingcomprises an electrically conductive material and further comprising anelectrically conductive washer disposed on the revolute joint betweenthe first jaw and the housing for providing the first electricalconduction path.
 11. The apparatus of claim 1 wherein the portion of thecontrol link in sliding contact with the second jaw comprises aconductive tab having a surface that contacts the second jaw.
 12. Theapparatus of claim 1 wherein the lever arms associated with the firstand second jaws each comprise a slot and wherein the yoke comprises apin slidingly received within the respective slots for providing themechanical coupling between the yoke and the lever arms.
 13. Theapparatus of claim 12 wherein the slot comprises an arcuate slot. 14.The apparatus of claim 12 wherein the pin comprises: an insulatedportion received within the slot in the lever arm of the first jaw; anda conductive pin portion received within the slot in the lever arm ofthe second jaw for completing the second electrical conduction pathbetween the control link and the second jaw.
 15. The apparatus of claim1 wherein the housing comprises an insulating material and wherein thefirst electrical conduction path between the housing and the first jawis provided by a conductor running through the housing and having aportion in sliding contact with the first jaw.
 16. The apparatus ofclaim 1 further comprising a linkage extending between the lever armassociated with at least one of the first and second jaws and the yokefor providing the mechanical coupling between the yoke and the leverarm.